Idea

noun

1. An abstract archetype of a given thing, compared to which real-life examples are seen as imperfect approximations; pure essence, as opposed to actual examples.
2. The conception of someone or something as representing a perfect example; an ideal.
3. The form or shape of something; a quintessential aspect or characteristic.
4. An image of an object that is formed in the mind or recalled by the memory.

   "The mere idea of you is enough to excite me."

5. More generally, any result of mental activity; a thought, a notion; a way of thinking.